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When it comes to ventilation specifically, first, West Virginia law does not specify a specific biogas threshold concentration to mark the boundary between manageable and hazardous levels.
Instead, by 1898 (with some amendments), the state required every mine to provide at least one hundred cubic feet of fresh air per minute to each miner. The U.S. Bureau of Mines and the U.S. Coal Commission have expressed concern about the lack of stricter regulation because of the belief that many mines may be incorrectly classified as non-gas mines. Second, the first law of 1883 and the revised editions of 1898 and 1901 do not clearly state what should be done in the presence of biogas. This flexibility may be in the owner's financial interest by leaving open the possibility of using fans or other methods, but inspectors often take different positions—the U.S. Bureau of Mines also notes that typically, inspectors either expect and recommend the use of mechanical ventilation or, where one already exists, praise the use of mechanical ventilation. Two typical examples of this: the data available for reporting.
It was revealed that mechanical ventilation was rapidly adopted despite the lack of legal requirements. The percentage of mines with fans rose from 1% in 1883 to about a quarter in the early 90s of the 19th century, and rose to 76% in 1909. Although West Virginia started late in coal production, it was not much different from Pennsylvania's coalfields, which also contained asphalt. However, at the end of the 2010s, furnaces were still the preferred ventilation method for about 20% of mines. Legislation related to explosions is also inadequate.
First of all, coal dust is sometimes the main cause of explosionsTherefore, in the presence of coal dust, methane is flammable or explosive at very low levels. In addition, the coal dust itself can ignite, for example by blasting. Explosions involving coal dust also tend to be larger, as the dust can propagate the initial explosion throughout the mine. This seems to apply to West Virginia, which passed a state law in 1901 making it mandatory to sprinkle coal dust or stone dust, however, it has been argued that the disposal of coal dust is limited to mines producing "dangerous amounts" of gas, and even worse, the practice of connecting mines for ease of construction and transportation has thus facilitated the spread of explosions, which has been banned in some states but not in West Virginia. Unlike some other U.S. states (Dix), where mine chiefs or certain types of miners do not require qualifications untrained and sometimes foreigners (who do not speak English), the use of miners as "safety explosives" for shooters was first recorded in 1908 (Forbes and Auennes "firing solids" or blasting without hollowing out coal beforehand was a procedure because it increased the productivity of miners.
The problem is that this practice uses a large amount of powder, and therefore increases the danger of explosion, shooting solids has been banned in many countries and neighboring states, but is allowed in West Virginia and is common. In 1906, an inspector declared that "many [miners] insisted on doing so." Similarly, a report reviewing the security situation concluded that "the practice of shooting solids remains largely practiced throughout the state" (West Virginia Legislature Joint Special Committee. However, the same report also acknowledges that many companies do not allow and promote this practice. In fact, in the first report on emitting solids in 1911, the U.S. Geological Survey reported that 1% of the coal was extracted in this way. Our aim is to evaluate the determinants of adopting the latest security technologies.
We believe that technology adoption is the choice of coal owners, driven by the associated costs and benefits. We started by quantifying mine characteristics to determine which type of mine preferred mechanical ventilation. We then delve deeper (in the discussion section) into the possible motivations of mine owners to replace or not replace older technologies. The period considered in our model is 1898-1907. Beginning in 1897, West Virginia — in its annual WVDM report — surveyed all mines that claimed to employ at least 10 miners. However, the explosion data reported in the 1897 WVDM Annual Report did not agree with the data reported in the U.S. Bureau of Mines' Revised Report, and we used their information as support.
Therefore, we decided to skip the first year. By 1907, the increasing number of mergers, acquisitions, and mine name changes meant that the proportion of mines providing necessary information, such as ventilation methods, had grown significantly and we were unable to provide it. However, in the period 1898-1907, against the backdrop of economic expansion and lack of legal obligations, Van's adoption was quite rapid. In principle, to evaluate a group, observation of the mine during this period is required for at least two years. Therefore, only one observation year of mines was not used.
For all mine-year observations, the dependent variable is set to 0 if the mine is still ventilated by natural ventilation, furnace ventilation, or other (typically steam) methods; If the mine has been converted to mechanical ventilation, the dependent variable is set to 1. Nine mines have been abandoned as they switched from mechanical ventilation to furnace ventilation. These mines do not seem to have a clear outline, at least in terms of quantitative characteristics. There are two exceptions: they are non-gas mines, which have almost no record of explosions (there was only one explosion in a mine during the period under review, and it was clearly small). The qualitative information provided by the inspectors did not help much on this particular issue, as they did not appear to comment on the reasons for the replacement.
One mine changed owners the year before, while in the other, the owner may have been experimenting with different ventilation methods. We will return to this in the second section. Inspectors' comments throughout the annual report indicate that fans and older technology are mutually exclusive. In our sample, only eight mines that had been observed for at least two years reported having both fans and stoves. Because in these cases, one stove may be available as a backup, perhaps temporarily, we decided to set the dependent variable to 1. Inevitably, the group is unbalanced.
As with Boal, data on some influencing variables is sometimes missed, and mines sometimes fail to match in consecutive annual reports because mines have not operated or changed names in all years. The main panel consists of 680 mines and 2,216 observations. Our primary empirical analysis consists of estimating a logistic model, which, due to the dependent variable, is a dichotomous employed. As a starting point, we rely on mixed-spec and random-effects panel approaches. The random-effects model assumes that unobserved effects are independent of explanatory variables. This may be a bold assumption.
Mine-specific characteristics such as geological conditions and management practices (not reported in the annual report) may be relevant with other explanatory variables, such as productivity, however, the gas/gas-free state of the mine (a key explanatory variable) has not changed over time (in technical terms, the internal variation of our biogas variable is zero). Therefore, we also run correlated random-effects (CRE) models. As described above (in the introduction), this method estimates the effects in random-effects models. In practice, this allows time-invariant variables to be included in effective fixed-effect methods. The remaining explanatory variables change over time. The robust standard error is clustered by me across all norms.
Table 1 describes the dependent and explanatory variables at the mine level. In our sample, 64% of the annual mine observations were ventilated by fans. Explanatory variables reflect mine characteristics related to cost and benefit factors. To mitigate endogeneity problems, each explanatory variable is assigned a value from the previous year, which means that the mine needs to be observed for at least three years. The second benefit is associated with the explosion. Previous explosions at the mine provided mine owners with information about the likelihood of future explosions and the potential advantages of mechanical ventilation.
Thus, eyewitnesses to the explosion were examined "with a view to determining, where possible, means of preventing these catastrophic explosions" (In this case, after the explosion at the Fort Berry Coal Mine (Southern Coal Transportation Company), an expedition visited the mine to investigate the cause of the explosion. The expected effect of the number of explosions on the adoption of more powerful mechanical ventilation systems is clearly positive. We consider all explosions, both those that cause death and/or injury and those that have no casualties. However, the magnitude of this variable's influence is difficult to predict because there is little quantitative information on the cost of an explosion. As stated by mine owners, miners, and inspectors from several basins, the explosion could disrupt mining activities or even destroy mines, resulting in high costs, in his final report, the West Virginia Legislature Joint Select Committee noted that after the explosion, "thousands of dollars in property damage certainly and unexpectedly followed." Similarly, a group of West Virginia miners declared:
Legal damages and litigation aside, going back to the cold business fact that delays and interruptions in coal mine work caused by just one accident can cost more than the work that could have prevented the accident, and any serious disaster could result in thousands of dollars in labor costs and thousands of dollars in other business losses and disruptions. The cost of a big explosion in Tucker County to "start (mine) work" (before considering any possible lawsuits) is estimated at $3,888 (Joint Special Committee of West Virginia Legislatures). However, the total cost of each explosion can vary greatly, depending on factors such as the size of the explosion and the amount of compensation. Moreover, judging by statistics, explosions are not common . Most mines do not experience an explosion in a given year, and the threat may be distant.
Of our main sample of 2216 mine-year observations, only 48 have exploded. Another potential benefit of adopting mechanical ventilation has to do with the scale of mine operations, which can be measured by the size of the workforce. The report provides information on underground workers. Large mines that employ more miners may benefit from mechanical ventilation for two main reasons. First, they need more fresh and fast-moving air. As one inspector wrote, "This (Roanoke) coal mine employs 60 workers, and 6 mules are used to transport coal."
The ventilation of the mine is generated by a furnace, which does not provide enough air volume for those working underground". Second, more miners means a higher risk of explosion. The final benefit of installing fans "The least capable and skilled miners have established safety within the mine" is the mechanization of coal mining, measured in the share of output mined by the machine. Early mechanization brought its own explosion hazard based on the generation of coal dust and sparks, and the West Virginia coalfield mechanization was rapid. During the period considered by our model, the proportion of machine-mined output increased from 7.9% to 36.7% (USGS). The potential cost of adopting new technologies must also be considered in the model.
A priori, there are reasonable grounds to expect a positive correlation between productivity and the adoption of mechanical ventilation. More productive coal mines will find it easier to obtain financing for installing wind turbines, with high upfront costs – as discussed in section 1. Regarding further geological conditions (i.e. the presence of biogas) in mines that affect the benefits or costs of technology adoption, the lack of depth information may be a limiting factor, as ventilation may become more important as depth increases Unfortunately, the WCU report did not comment on this.